1. Field of the Invention
The present invention relates in general to air conditioning systems used in motor vehicles, and more particularly, to automotive air conditioning systems of a type which effects not only air conditioning in the vehicle but also air ventilation in the same.
2. Description of the Prior Art
Hitherto, various air conditioning systems of the above-mentioned type have been proposed and put into practical use particularly in the field of motor vehicles. In fact, the air conditioning systems of such type are very useful particularly in a case wherein some of passengers in the vehicle are smokers.
Some of conventional air conditioning systems of this type are disclosed in Japanese Patent First Provisional Publications Nos. 60-252019 and 60-252020.
In these systems disclosed, a known air conditioner unit including an evaporator core, a heater core and a blower is installed in a front portion of the vehicle, and a ventilation device is further employed. The air conditioner unit has a plurality of conditioned air outlets exposed to a front portion of the passenger cabin of the vehicle. The ventilation device comprises an air ventilation duct mounted beneath the ceiling of a passenger cabin and an electric blower mounted in the duct. The ventilation duct has an air intake opening exposed to the upper portion of the passenger cabin. Upon energization of the blower, the ventilation duct intakes air from the passenger cabin and discharges the same to outside of the vehicle. With this, the contaminated air, that is, air contaminated with tobacco or cigarette smoke or the like is enforcedly discharged to outside of the vehicle.
Such air discharging is useful also under operation of a heater of the air conditioner in winter. That is, usually, under operation of the heater, due to the nature of things, an upper portion of the passenger cabin is more heated than a lower portion, which tends to give uncomfortable feeling to the passengers. Furthermore, the heating of the passenger cabin by the heater tends to cause formation of undesired mist on windows particularly in a case wherein many passengers are in the vehicle. In these cases, the air discharging is carried out by starting the ventilation device.
Furthermore, in summer, such air discharging is effective also in achieving a quick cooling in the hot passenger cabin of the vehicle which has been parked for a long time under the blazing sun. That is, in such case, prior to starting the cooler of the air conditioner, the hot air in the passenger cabin is discharged to outside by operating the ventilation device.
However, in fact, the above-mentioned conventional ventilation devices have the following drawbacks due to their inherent constructions.
That is, under operation of the heater in winter, starting the air ventilation device tends to cause the hot air from the air outlets of the air conditioner unit to be directed toward heads of the passengers due to positioning of the air intake opening of the ventilation duct at the ceiling of the passenger cabin. This phenomenon makes the passengers uncomfortable irrespective of the operation of the ventilation device. Furthermore, such directed flow of hot air tends to produce hot air pockets at various portions in the passenger cabin, which cause formation of mist on various portions of the windows.
Furthermore, under operation of the cooler in summer, starting the ventilation device tends to cause the cooled air from the air outlets of the air conditioner unit to be directly sucked by the air intake opening of the ventilation duct. In this case, effective and quick cooling of the passenger cabin is not expected. This undesirable phenomenon is marked particularly in air conditioners of automatic type in which flowing direction, flowing velocity and temperature of the conditioned air blown into the passenger cabin are automatically adjusted in accordance with conditions of the passenger cabin and those of the outside of the passenger cabin. This direct discharging of the conditioned air furthermore tends to produce disagreeably warm air pockets in the vicinity of the rear seat.
Furthermore, due to positioning of the air intake opening of the ventilation duct at the ceiling, it tends to occur that air contaminated or smoked by one passenger is forced to flow over the face of the other passenger before being sucked into the air intake port of the ventilation duct. This is quite uncomfortable to the other passenger.